Chemical Analysis

Question 1

which cations do you test for using the flame method?

Answer 1

Li+, Na+, K+, Ca2+, Cu2+

Question 2

what cations do you test for using NaOH solution?

Answer 2

NH4+, Cu+, Fe2+, Fe3+, Al3+, Ca2+

Question 3

Li+ flame colour?

Answer 3

(crimson) red

Question 4

Na+ flame colour?

Answer 4

orange

Question 5

K+ flame colour?

Answer 5

lilac

Question 6

Ca2+ flame colour?

Answer 6

brick red

Question 7

Cu2+ flame colour?

Answer 7

green

Question 8

ammonia test?

Answer 8

mix NaOH, heat it up over bunsen burner, and red litmus paper turns blue if positive

Question 9

Cu2+ and NaOH

Answer 9

creates a blue ppt = Cu(OH)2

Question 10

Fe2+ and NaOH

Answer 10

creates a green ppt = Fe(OH)2

Question 11

Fe3+ and NaOH

Answer 11

creates a brown ppt = Fe(OH)3

Question 12

Al3+ and NaOH

Answer 12

creates a white ppt, but does dissolve excess - so becomes colourless again

Question 13

Ca2+ and NaOH

Answer 13

creates a white ppt, but doesn’t dissolve excess - stays white

Question 14

how do you test for sulphates?

Answer 14

adding barium chloride and HCl

Question 15

why is an acid added for a sulphate test?

Answer 15

gets rid of any unwanted carbonate ions

Question 16

what happens if it is positive for sulphate?

Answer 16

white ppt

Question 17

how do you test for halides?

Answer 17

add silver nitrate and nitric acid

Question 18

what colour ppt is made when positive for Cl-

Answer 18

white ppt

Question 19

what colour ppt is made when positive for Br-

Answer 19

cream ppt

Question 20

what colour ppt is made when positive for I

Answer 20

yellow ppt

Question 21

how to test for carbonates?

Answer 21

add limewater Ca (OH)2 and HCL

Question 22

what happens when the test is positive for carbonates?

Answer 22

milky/cloudy white & effervescence

Question 23

test for hydrogen

Answer 23

squeaky pop test

Question 24

test for oxygen

Answer 24

lit splint test

Question 25

test for carbon dioxide

Answer 25

limewater

Question 26

test for water

Answer 26

1) copper sulphate 2) cobalt chloride paper blue to pink

Question 27

test for chlorine

Answer 27

damp blue litmus paper turns red then white (bleaches)